1. Field of Use
This invention relates generally to industrial ovens for heating and/or drying products, such as for example, for drying products after a painting operation. In particular, it relates to an oven constructed to reduce heat losses.
2. Description of the Prior Art
Industrial ovens for indoor and outdoor use are well-known in the art and are typically of a butt joint or a tongue and groove construction. The walls of prior art ovens often have a plurality of vertical panels, with tongue and groove joints between the panels, which abut to form an inner and outer wall.
Expansion and contraction of the oven walls of the prior art construction occurs during the oven's operation, and the joint between the adjacent panels must accommodate this expansion. The construction of one type of prior art panel includes a panel end which is generally of U-shaped configuration when viewed in plan, including a central web that conducts heat outwardly thru the wall at each joint. In other types, the joints do not adequately close and a gap then remains through which heat may readily escape.
Prior art ovens with insulated side walls enclosing an interior heating chamber and having an inner and outer skin include the oven described in U.S. Pat. No. 4,059,398, issued to Zimmer et al on Nov. 22, 1977. The wall has an insulating air space, but the air space communicates with the ambient outside the oven and requires a fan to force cooling ambient air therethrough in an attempt to prevent the outer skin from becoming excessively hot.
An oven having a structural steel framework for supporting the inner and outer skins of walls is shown in U.S. Pat. No. 3,717,939, issued to Mitchell on Feb. 27, 1973. The horizontal structural elements are rigidly connected at their ends to the vertical structural elements. This rigid connection is undesirable because as the horizontal structural elements are heated during operation of the oven, they expand outwardly and towards the vertical elements to place damaging stress on the framework. In addition, some of the vertical structural elements are outside of the walls, permitting conduction heat losses from those elements.